
Compound (I) is disclosed in U.S. Pat. No. 8,148,526 as an HDAC inhibitor. Example 2 of U.S. Patent Application Publication No. 2015/0099744 discloses a synthesis of compound (I). As detailed herein in Example 3, this synthesis procedure resulted in the formation of significant amounts of de-chlorination and chlorine-migration side products. These impurities have solubilities that are similar to the solubilities of the desired intermediates. Removal of the impurities is very challenging, requiring lengthy work-ups, involving numerous washes, triturations and crystallizations. Triturations, in particular, are known to be inefficient and unscalable processes. When compound (I) was prepared according to Example 2, the necessary purification steps resulted in a significant loss of desired intermediates, led to a modest overall yield, and rendered further industrial scale up of the synthesis route unpractical. There remains a need for new methods for the synthesis of compound (I), and related compounds, that minimize the formation of impurities, and that are amenable to industrial scale-up.